package com.example.yuanqin

import androidx.test.platform.app.InstrumentationRegistry
import androidx.test.ext.junit.runners.AndroidJUnit4

import org.junit.Test
import org.junit.runner.RunWith

import org.junit.Assert.*

/**
 * Instrumented test, which will execute on an Android device.
 *
 * See [testing documentation](http://d.android.com/tools/testing).
 */
@RunWith(AndroidJUnit4::class)
class ExampleInstrumentedTest {
    @Test
    fun useAppContext() {
        // Context of the app under test.
        val appContext = InstrumentationRegistry.getInstrumentation().targetContext
        assertEquals("com.example.yuanqin", appContext.packageName)
    }

}
class Solution {
    fun mirrorTree(root: TreeNode?): TreeNode? {
        if (null == root){
            return null
        }
        val leftChild = root.left
        val rightChild = root.right
        root.left = mirrorTree(rightChild)
        root.right = mirrorTree(leftChild)
        return root
    }
//
//    fun mirrorTree1(root: TreeNode?): TreeNode? {
//        if (null == root){
//
//        }
//        val nodes = arrayOfNulls<TreeNode>(2)
//        nodes[0] = root?.right
//        nodes[1] = root?.left
//        while (true){
//            for (childNode in nodes.reversed()){
//
//            }
//        }
//        return buildChildNode(childArray)
//    }


}
class TreeNode(var `val`: Int) {
    var left: TreeNode? = null
    var right: TreeNode? = null
}